WO2008138482A1 claims a process for making polyurethane polymer obtained when at least one polyol is reacted with a polyisocyanate in the presence of catalysts and in the presence of at least a sulfurous compound selected from hydrogen sulfite and disulfite. The sulfurous compound described in this disclosure influence the reactivity of the foam mixture. If the amount of sulfurous compound is large the productivity may not be maintained and the catalyst level need to be adjusted (increase) to keep the foam rise profile similar to the standard mixture without the sulfurous compound. Thus, the sulfurs compounds of WO2008138482A1 are characterized by reducing aldehyde emanations but can be detrimental to foam reactivity beyond the recommended use level.
GB871291 relates to the production of polyester-urethane foam or cellular products which are hydrophilic and are capable of swelling in water and absorb large quantities of water. The disclosure provides a method of imparting hydrophilicity to polyester-polyurethane foam by introducing sulfonate and/or sulfonic acid groups which comprise treating a foamed polyester-urethane mass with an aqueous solution of an alkali metal sulfite or bisulfate at a temperature from room temperature to 100° C.
The previously described patents are hereby incorporated by reference.